MB-11477: Fix crash in process items due to no default argument

Change-Id: I4932ce2094273ce1e877bea70c8e279e232d35f2
Reviewed-on: http://review.couchbase.org/38451
Reviewed-by: abhinav dangeti <abhinav@couchbase.com>
Reviewed-by: Sriram Ganesan <sriram@couchbase.com>
Tested-by: Michael Wiederhold <mike@couchbase.com>